#pragma once

#include <iostream>
#include <queue>
#include <pthread.h>
#include <vector>
#include <functional>
#include "Log.hpp"
#include "Thread.hpp"
#include "LockGuard.hpp"

namespace ThreadNs
{
    static const int default_num = 5; // 默认线程池中的线程个数

    class ThreadData
    {
    public:
        ThreadData(const std::string &threadname)
            : _threadname(threadname)
        {
        }

        ~ThreadData()
        {
        }

    public:
        std::string _threadname;
    };

    template <class T>
    class ThreadPool
    {
    private:
        ThreadPool(int thread_num = default_num)
            : _thread_num(thread_num)
        {
            pthread_mutex_init(&_mutex, nullptr);
            pthread_cond_init(&_cond, nullptr);

            // 构建指定个数的线程
            for (int i = 0; i < _thread_num; i++)
            {
                // 待优化
                std::string threadname = "thread-";
                threadname += std::to_string(i + 1);

                ThreadData td(threadname);

                Thread<ThreadData> t(threadname,
                                     std::bind(&ThreadPool<T>::ThreadRun,
                                               this, std::placeholders::_1),
                                     td);

                _threads.push_back(t);
                lg.LogMessage(Info, "%s is created...\n", threadname.c_str());
            }
        }

        ThreadPool(const ThreadPool<T> &tp) = delete;
        const ThreadPool<T> &operator=(const ThreadPool<T> &tp) = delete;

    public:
        // 有线程安全问题
        static ThreadPool<T> *GetInstance()
        {
            if (instance == nullptr)
            {
                LockGuard lockguard(&sig_lock);
                if (instance == nullptr)
                {
                    lg.LogMessage(Info, "创建单例成功...\n");
                    instance = new ThreadPool<T>();
                }
            }

            return instance;
        }

        bool Start()
        {
            // 启动
            for (auto &thread : _threads)
            {
                thread.Start();
                lg.LogMessage(Info, "%s is running ...\n", thread.ThreadName().c_str());
            }

            return true;
        }

        void ThreadWait(const ThreadData &td)
        {
            lg.LogMessage(Debug, "no task, %s is sleeping...\n", td._threadname.c_str());
            pthread_cond_wait(&_cond, &_mutex);
        }

        void ThreadWakeup()
        {
            pthread_cond_signal(&_cond);
        }

        void CheckSelf()
        {
            // 1. _task_num > _task_num_high_water && _thread_num < _thread_num_high_water
            // 创建更多线程，并更新_thread_num

            // 2. _task_num == _task_num_low_water && _thread_num >= _thread_num_high_water
            // 把自己退出了，并且更新_thread_num
        }

        void ThreadRun(ThreadData &td)
        {
            while (true)
            {
                // 取任务
                CheckSelf();
                T t;
                {
                    LockGuard lockguard(&_mutex);
                    while (_q.empty())
                    {
                        ThreadWait(td);
                        lg.LogMessage(Debug, "thread, %s wake up.\n", td._threadname.c_str());
                    }

                    t = _q.front();
                    _q.pop();
                }

                // 处理任务
                t();
                // lg.LogMessage(Info, "%s handler task %s done, result is: %s\n", \
                td._threadname.c_str(), t.PrintTask().c_str(), t.PrintResult().c_str());
            }
        }

        void Push(T in)
        {
            // lg.LogMessage(Debug, "other thread push a task, task is: %s\n", in.PrintTask().c_str());
            {
                LockGuard lockgurad(&_mutex);
                _q.push(in);
                ThreadWakeup();
            }
        }

        // for debug
        void Wait()
        {
            for (auto &thread : _threads)
            {
                thread.Join();
            }
        }

        ~ThreadPool()
        {
            pthread_mutex_destroy(&_mutex);
            pthread_cond_destroy(&_cond);
        }

    private:
        std::queue<T> _q; // 任务队列
        std::vector<Thread<ThreadData>> _threads;
        int _thread_num; // 线程个数
        pthread_mutex_t _mutex;
        pthread_cond_t _cond;

        static ThreadPool<T> *instance;
        static pthread_mutex_t sig_lock;

        // 扩展1:
        int _task_num;

        int _thread_num_low_water;
        int _thread_num_high_water;
        int _task_num_low_water;
        int _task_num_high_water;

        // 扩展2:多进程+多线程
    };

    template <class T>
    ThreadPool<T> *ThreadPool<T>::instance = nullptr;

    template <class T>
    pthread_mutex_t ThreadPool<T>::sig_lock = PTHREAD_MUTEX_INITIALIZER;
}